The Clancy Brothers

One night at the Gaslight, Llewyn Davis catches a performance by an Aran sweater-clad Irish folk quartet, who were no doubt modeled after the Clancy Brothers, a traditional singing group active in the Greenwich Village folk scene during the time period captured by the film. As the story goes, upon hearing a rumor that it was going to be a cold winter in New York, the Clancys' mother mailed her sons the thick sweaters that became their trademark.